1. Field of the Invention
This invention relates to a vibration insulator and in particular, to a cylindrical rubber vibration insulator having a bracket for securing it in position on a vehicle engine, a vehicle body, etc., with the rubber being vulcanization-bonded to the inner peripheral surface of the vibration insulator.
This invention also relates to an improved method of manufacturing a bracket for securing a vibration insulator bushing in position.
2. Description of the Related Art
Conventionally, a bracket for a rubber vibration insulator of this type has consisted of a cylindrical member, into which the vibration insulating rubber is forced so as to be held therein, and fastening leg sections welded to the cylindrical member.
A problem with the conventional rubber vibration insulator described above is that axial displacement of the rubber is prevented solely by the compressive force of the rubber resulting from it being forced into the cylindrical member. Therefore, the force with which the rubber is forced into the cylindrical member must accordingly be large, which leads to various problems. For example, the wall thickness of the cylindrical member has to be made large. Further, the operation of forcing the rubber into the cylindrical member requires a large-sized apparatus.
FIG. 10 shows an example of a conventional bracket. Referring to the drawing, a bracket 101 comprises a cylindrical holder section 111 and leg sections 112 and 113 respectively welded to either side of the lower peripheral surface of the holder section 111. The bracket 101 is fastened to a base body, such as a vehicle frame, by means of mounting holes 117 provided in the leg sections 112 and 113. A vibration insulator bushing 102 is held in a bore 114 of the cylindrical holder section 111. This vibration insulator bushing 102 consists of concentric inner and outer cylinders 121 and 122 and a rubber vibration insulator 123 disposed between these cylinders and bonded thereto. The outer cylinder 122 is forced into the bore 114, and the inner cylinder 121 is connected to a vibrating body, such as an engine.
A problem with the above-described conventional bracket is that the holder section and leg sections are separately prepared before being welded together, so that it is impossible to avoid the disadvantages of parts storage and positioning during welding, which should be accurate. Consequently, the conventional bracket inevitably involves high production costs. Further, there is the danger of the holder section being distorted during the welding of the leg sections, resulting in deformation of the bore of the holder section, although errors in the bore diameter must be restrained to be as small as possible for the vibration insulating bushing to be smoothly inserted into the bore and reliably held therein.